A writing electromagnet is used in a read/write head to orient magnetic fields in a recording medium of a magnetic storage device. An example is the read/write head of a computer hard disk or a magnetic recording tape. The read/write head is positioned closely adjacent to the recording medium, separated from the recording medium by an air bearing that does not allow them to touch. A data bit is written onto an area of the recording medium using the writing portion of the read/write head by locally changing its magnetic state. That magnetic state is later sensed by a magnetoresistive sensor to read the data bit.
The writing portion of the read/write head utilizes a generally U-shaped electromagnet with an inductive coil passing through the electromagnet. The ends of the arms of the electromagnet, termed the poles, face the air bearing surface (ABS) that defines one side of the air bearing. When an electrical current is passed through the inductive coil, a magnetic field is generated that extends between the poles and into the adjacent portion of the recording medium “writing” a data bit to that portion of the recording medium.
A continuing trend in the magnetic recording industry is to increase the density of information stored in the recording medium, and to increase the speeds of writing to and reading from the recording medium. To do so, the size of the writing electromagnet in the writing portion of the read/write head must be reduced. In current technology, the writing portion (as well as the reading portion) is fabricated by techniques comparable to those used in the microelectronics industry.
The fabrication of the read/write head presents some different problems, however, than those encountered in microelectronics technology. For example, in some designs a part of the pole structure and the inductive coil of the writing structure are high-vertical aspect ratio metallic features of different compositions that lie in the same plane. It is difficult to deposit these features with the required geometries and separations, so that no electrical shorting occurs between the turns of the inductive coil or between the inductive coil and the pole structure, and in the ever-finer scales required to permit the increased information density in the recording medium.
There is a need for an approach that allows the read/write head, and in particular the writing portion of the read/write head, to be fabricated in the required geometries but with a very small coil pitch and high aspect ratio.